Introduction
This guide discusses the mechanics of Kunkka's spells and gives advice and strategy for using his spells to properly.
Ghost Ship
Ghost Ship Targeting and Damage
Ghost Ship only deals damage where it crashes, it does NOT deal damage when it passes through enemies.
Ghost Ship will always travel its minimum distance (950 units), even if it is targeted closer than that range.
If you cast Ghost Ship at 950 range or greater the ship will crash at the exact point you targeted.
How far is 950 units?
The Ranges of Meat Hook and Ghost Ship

Meat hook has a range of 1000 units, Ghost Ship 950.
Ranges With Reference Creep battle

This image shows meathook fully extended to 1000 units and Ghost Ship traveling 950 units with reference to one of the most ubiquitous sights in DotA - creeps engaged in battle. I tried to line up the spells in parallel to the lines of the ranged creeps, but Kunkka is aiming a bit of a diagonal. What you should take away from this picture is that 950 units is bit farther than the distance between the ranged creeps when they are attacking (they have 500 range each but overlap by about 100-200 units, and generally aren't perfectly aligned).
Ghost Ship has an AoE 425 units
What does 425 AoE look Like?
Here is a picture that can help you gauge the AoE of Ghost Ship

In this picture, Ghost Ship was targeted at the ranged creep, now pawned. Burn into your memory distances of the two melee creeps. One was inside the AoE of Ghost Ship and was pawned, the other, however, was not.
Comboing X Marks the Spot to Ghost Ship
In order to combo X Marks the Spot to Ghost Ship by targeting Ghost Ship on the X you need:
To cast X Marks the Spot from outside of 575 range
Hence, at least level 2 X Marks the Spot
If these criteria are fulfilled, Ghost Ship’s AoE will overlap onto the X from X Marks the Spot
See the 2nd example in the following section for an example of pulling off such a combo and a more detailed step by step explanation.
More Facts about Ghost Ship
425 detection AoE to grant Rum (width)
Ghost Ship spawns 1000 units behind Kunkka (unless that's outside the map boundaries)
The total distance the ship travels is 1950 (950 from the hero)
The movement speed is 650
Torrent
Torrent has insane range: 1500
The Bubbles are Invisible to Enemies
The bubbles that appear on the ground when you cast Torrent are invisible to your enemies, though your casting animation can still give you away. Hence, when trying to land Torrent without an initiating disable, you should take advantage of your aforementioned insane range to cast the spell from where your enemy will not have sight of you. See Kunkka Torrent Question - Response by Mechanics Moderator
Aoe of 225 units
The AoE of Torrent is the same as the target cursor. Thus, the AoE is small, but like Ghost Ship's AoE it is still significantly larger than the spell effect's graphic, the bubbles.
The Gas in Torrent’s Graphical Effect Plays Once
While the Torrent’s bubbles play on some sort of loop or are so small you cannot use them as to track the wind up’s progress, the gas part of the graphic only plays once. Right before the 2 second wind-up finishes the gas finishes rising and begins to dissipate … if you have your spell detail and other graphics on high.
Landing Torrent against Moving Heroes
A 300 ms hero with boots (350 ms) can walk from his ranged creep, to a bit before the enemy ranged creep.
X Marks the Spot
Cast Return to Fake Casting Torrent
A clever trick i learned was that if you cast return with X marks the spot and no X, you can usually freak the enemy out into thinking you used torrent.